Blending of economic reduced oxygen, summer gasoline

ABSTRACT

Provided is a novel summer gasoline composition which is substantially free of oxygenates, contains less than 20 ppm sulfur, and is in compliance with the California Phase 3 Predictive Model. The gasoline composition is suitable for use in the summer, i.e., having a Reid vapor pressure of 7.2, and more preferably 7.0, or less, but also offers the advantages of low emissions while being substantially free of oxygenates. The method for blending the gasoline comprises blending streams from a refinery in a controlled manner to maintain compliance with the California Phase 3 Predictive Model.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 09/603,557,filed on Jun. 26, 2000, now abandoned, which in turn is acontinuation-in-part of application Ser. No. 09/266,901, filed on Mar.12, 1999, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to fuels, particularly gasoline fuelswhich are substantially oxygenate free. More specifically, the presentinvention relates to a summer, low-emission gasoline fuel which complieswith the California Predictive Model, as well as ASTM D4814, and is alsosubstantially oxygenate free.

2. Brief Description of the Prior Art

One of the major environmental problems confronting the United Statesand other countries is atmospheric pollution caused by the emission ofpollutants in the exhaust gases and gasoline vapor emissions fromgasoline fueled automobiles. This problem is especially acute in majormetropolitan areas where atmospheric conditions and the great number ofautomobiles result in aggravated conditions. While vehicle emissionshave been reduced substantially, air quality still needs improvement.The result has been that regulations have been passed to further reducesuch emissions by controlling the composition of gasoline fuels. Thesespecially formulated, low emission gasolines are often referred to asreformulated gasolines. California's very strict low emissions gasolineis often referred to as California Phase 2 or Phase 3 gasoline. In thesegasolines, oxygen-containing hydrocarbons, or oxygenates, are oftenblended into the fuel.

Congress and regulatory authorities, such as CARB (the California AirResources Board), have focused on setting specifications for lowemissions, reformulated gasoline. The specifications, however, requirethe presence of oxygenates in gasoline sold in areas that are not incompliance with federal ambient air quality standards for ozone, and thedegree non-attainment is classified as severe, or extreme. Among theemissions which the reformulated gasoline is designed to reduce, arenitrogen oxides (NO_(x)), hydrocarbons (HC), and toxics (benzene,1,3-butadiene, formaldehyde and acetaldehyde). A reduction in theseemissions has been targeted due to their obvious impact upon the air webreathe and the environment in general.

Oxygenated gasoline is a mixture of conventional hydrocarbon-basedgasoline and one or more oxygenates. Oxygenates are combustible liquidswhich are made up of carbon, hydrogen and oxygen. All the currentoxygenates used in reformulated gasolines belong to one of two classesof organic molecules: alcohols and ethers. The Environmental ProtectionAgency regulates which oxygenates can be added to gasoline and in whatamounts.

The primary oxygen-containing compounds employed in gasoline fuels todayare methyl tertiary butyl ether (MTBE) and ethanol. While oxygen is inmost cases required in reformulated gasolines to help effect lowemissions, the presence of oxygenates such as MTBE and ethanol ingasoline fuels has begun to raise environmental concerns. For example,MTBE has been observed in drinking water reservoirs, and in a fewinstances, ground water in certain areas of California. Ethanol raisesconcerns regarding hydrocarbon emissions upon fueling the car. As aresult, the public is beginning to question the benefits and/orimportance of having oxygen based cleaner burning gasolines, if theysimply pollute the environment in other ways. Furthermore, oxygenatessuch as ethers also have a lower thermal energy content thannon-oxygenated hydrocarbons, and therefore reduce the fuel economy ofgasoline fueled motor vehicles.

Thus, while some of the concerns with regard to gasoline fuelscontaining oxygenates, could be overcome by further safe handlingprocedures and the operation of present facilities to reduce the risk ofany spills and leaks, there remains a growing public concern with regardto the use of oxygenates in gasoline fuels. In an effort to balance theneed for lower emission gasolines and concerns about the use ofoxygenates it, therefore, would be of great benefit to the industry if acleaner burning gasoline without oxygenates could, be made whichcomplied with the requirements of the regulatory authorities (such asCARB). The availability of such a gasoline, which containedsubstantially no oxygenates, would allow the public to realize theenvironmental benefits of low emissions, yet ease the concern ofpotential contamination of ground waters, and the environment ingeneral, with oxygenates. Of benefit to the industry would also be theeconomics of such a low emission gasoline which contained substantiallyno oxygenates.

Accordingly, it is an object of the present invention to provide agasoline fuel, and a method of blending same, which can truly benefitthe environment and continue to be suitable for use as a motor gasoline.

Yet another object of the present invention is to provide such agasoline fuel, and method of blending same, which is specificallysuitable for the summer season, which offers considerable difficultiesin blending.

It is another object of the present invention to provide a summergasoline fuel, and method of blending same, which provides goodemissions, yet is substantially free of oxygenates.

It is yet another object of the present invention to provide an economicand commercially plausible method for blending such a summer gasolinefuel.

These and other objects of the present invention will become apparentupon a review of the following specification, the Figures of theDrawing, and the claims appended thereto.

SUMMARY OF THE INVENTION

In accordance with the foregoing objectives, there is provided by thepresent invention a method of blending a novel gasoline which meetsCalifornia Regulations and is suitable for use in the summer months,i.e., having a Reid vapor pressure in the range of about 7.20 or less,and more preferably about 7.00 or less, which has a sulfur content ofless than 20 ppm and is substantially free of oxygenates. The methodcomprises blending streams from a refinery, while maintaining the blendsubstantially free of oxygenates, in a controlled manner to maintaincompliance with the California Predictive Model. It is preferred thattesting of the blended fuel occurs during blending for compliance withthe California Predictive Model, with adjustments made in the blendsbased on the results of the testing to thereby maintain compliance withthe California Predictive Model.

Among other factors, the present invention is based in part upon therecognition that the blending process of some or all of thegasoline-component streams of an oil refinery, can be controlled, whileeliminating oxygenates, to successfully provide by an economic,continuous blending process a low-emission gasoline substantially freeof oxygenates which is in compliance with the California Code ofRegulations, and in particular the California Predictive Model, eitherthe Phase 2 or Phase 3 Predictive Model. The difficulty arises ineliminating oxygenates, as a significant difference in blending isrequired in the absence of oxygenates to achieve the requisite octanerating and fluid vapor pressure while also meeting the CaliforniaPredictive Model specifications. MTBE in particular is a high octane,low boiling, moderate RVP component and its elimination presentsconsiderable obstacles to successfully blending, in particular, a highoctane summer gasoline. Yet, it has been discovered that appropriateblending can occur to provide a commercially economic, low-emission,gasoline blend suitable for summer using the gasoline-component streamsof a refinery. Controlling the amount of sulfur to 20 ppm wt. or less,and more preferably 10 ppm wt. or less, helps significantly inmaintaining compliance with the California Predictive Model. Generally,testing on either a periodic or continuous basis of the blended streams,with subsequent adjustments in the blends based on the results of thetesting, is employed in order to maintain compliance with the CaliforniaPredictive Model. This is particularly preferred as the streams in arefinery can change in composition over time.

In another embodiment, the present invention provides one with a novel,summer gasoline which is substantially oxygenate free, containing 20 ppmwt. or less sulfur, and is in compliance with the California PredictiveModel. The compositions are preferably blended by the methods of thepresent invention.

BRIEF DESCRIPTION OF THE FIGURES OF THE DRAWING

FIG. 1 of the drawing schematically depicts a gasoline blending systemin accordance with the present invention.

FIG. 2 illustrates the relative number of conventional gasolines thatcan be blended.

FIG. 3 illustrates the relative number of low-emission gasolines thatcan be blended when containing oxygenates, and when containingsubstantially no oxygenates.

DETAILED DESCRIPTION OF THE INVENTION

Gasolines are well known fuels, generally composed of a mixture ofnumerous hydrocarbons having different boiling points at atmosphericpressure. Thus, a gasoline fuel boils or distills over a range oftemperatures, unlike a pure compound. In general, a gasoline fuel willdistill over the range of from about, room temperature to 437° F. (225°C.). This temperature range is approximate, of course, and the exactrange will depend on the conditions that exist in the location where theautomobile is driven. The distillation profile of the gasoline can alsobe altered by changing the mixture in order to focus on certain aspectsof gasoline performance, depending on the time of year and geographiclocation in which the gasoline will be used.

Gasolines are therefore, typically composed of a hydrocarbon mixturecontaining aromatics, olefins, naphthenes and paraffins, withreformulated gasoline most often containing an oxygen compound, i.e., anether such as methyl tertiary butyl ether. The fuels contemplated in thepresent invention are substantially oxygenate free unleaded gasolines(herein defined as containing a concentration of lead no greater than0.05 gram of lead per gallon which is 0.013 gram of lead per liter). Theanti-knock value (R+M)/2 for regular gasoline is generally at least 87,at least 89 for mid-range, and for premium at least 91, and generally atleast 92.

In an attempt to reduce harmful emissions upon the combustion ofgasoline fuels, regulatory boards as well as Congress have developedcertain specifications for reformulated gasolines. One such regulatoryboard is that of the State of California, i.e., the California AirResources Board (CARB). In 1991, specifications were developed by CARBfor California gasolines which, based upon testing, should provide goodperformance and low emissions. The specifications and properties of thereformulated gasoline, which is referred to as the Phase 2 reformulatedgasoline or California Phase 2 gasoline, are shown in Table 1 below.

TABLE 1 Properties and Specifications for Phase 2 Reformulated GasolineFlat Averaging Fuel Property Units Limit Limit Cap Limit Reid vapor psi,max.  7.00¹  7.00¹ pressure (RVP) Sulfur (SUL) ppmw  40 30  80 Benzene(BENZ) vol. %, max.  1.00 0.80  1.20 Aromatic HC vol. %, max.  25.0 22.0 30.0 (AROM) Olefin (OLEF) vol. %, max.  6.0 4.0  10.0 Oxygen (OXY) wt,%  1.8 (min)  0 (min)  2.2 (max)  3.5 (max) Temperature at deg. F. 210200 220 50% distilled (T50) Temperature at deg. F. 300 290 330 90%distilled (T90) ¹Applicable during the summer months identified in 13CCR, sections 2262.1(a) and (b); California requires adherence to ASTMspecifications.

Recently, Phase 3 regulations have been developed. At present, thegasoline can meet either Phase 2 or Phase 3 regulations, but beginningJan. 1, 2003, Phase 3 regulations must be met. The specifications andproperties of the reformulated California Phase 3 gasoline are shown inTable 2 below:

TABLE 2 Properties and Specifications for Phase 3 Reformulated GasolineFlat Average Fuel Property Units Limit Limit Cap Limit Reid vapor psi,max. 7.00 6.40-7.20¹ pressure (RVP) Sulfur (SUL) ppmw 20 15 60²/30³Benzene (BENZ) vol. %, max. 0.80 0.70  1.10 Aromatic HC vol. %, max.25.0 22.0  35.0 (AROM) Olefin (OLEF) vol. %, max. 6.0 4.0  10.0 Oxygen(OXY) wt, % 1.8 (min)  3.7⁴ 2.2 (max) Temperature at deg. F. 213 203 22050% distilled (T50) Temperature at deg. F. 305 295 330 90% distilled(T90) ¹Applicable during the summer months identified in 13 CCR,Sections 2262, 1(a) and (b); California requires adherence to ASTMspecifications. ²Jan. 1, 2004-Dec. 31, 2004. ³Beginning Jan. 1, 2005.⁴For ethanol only.

In Tables 1 and 2, as well as for the rest of the specification, thefollowing definitions apply:

Aromatic hydrocarbon content (Aromatic HC, AROM) means the amount ofaromatic hydrocarbons in the fuel expressed to the nearest tenth of apercent by volume in accordance with 13 CCR (California Code ofRegulations), section 2263.

Benzene content (BENZ) means the amount of benzene contained in the fuelexpressed to the nearest hundredth of a percent by volume in accordancewith 13 CCR, section 2263.

Olefin content (OLEF) means the amount of olefins in the fuel expressedto the nearest tenth of a percent by volume in accordance with 13 CCR,section 2263.

Oxygen content (OXY) means the amount of actual oxygen contained in thefuel expressed to the nearest tenth of a percent by weight in accordancewith 13 CCR, section 2263.

Potency-weighted toxics (PWT) means the mass exhaust emissions ofbenzene, 1,3-butadiene, formaldehyde, and acetaldehyde, each multipliedby their relative potencies with respect to 1,3-butadiene, which has avalue of 1.

Predictive model means a set of equations that relate emissionsperformance based on the properties of a particular gasoline formulationto the emissions performance of an appropriate baseline fuel.

Reid vapor pressure (RVP) means the vapor pressure of the fuel expressedto the nearest hundredth of a pound per square inch in accordance with13 CCR, section 2263.

Sulfur content (SUL) means the amount by weight of sulfur contained inthe fuel expressed to the nearest part per million in accordance with 13CCR, section 2263.

50% distillation temperature (T50) means the temperature at which 50% ofthe fuel evaporates expressed to the nearest degree Fahrenheit inaccordance with 13 CCR, section 2263.

90% distillation temperature (T90) means the temperature at which 90% ofthe fuel evaporates expressed to the nearest degree Fahrenheit inaccordance with 13 CCR, section 2263.

Toxic air contaminants means exhaust emissions of benzene,1,3-butadiene, formaldehyde, and acetaldehyde.

The pollutants addressed by the foregoing specifications include oxidesof nitrogen (NO_(x)), and hydrocarbons (HC), which are generallymeasured in units of gm/mile, and potency-weighted toxics (PWT), whichare generally measured in units of mg/mile.

The California Phase 2 and Phase 3 reformulated gasoline regulationsdefine a comprehensive set of specifications for a gasoline (Tables 1and 2). These specifications have been designed to achieve largereductions in emissions of criteria and toxic air contaminants fromgasoline-fueled vehicles. Gasolines which do not meet the specificationsare believed to be inferior with regard to the emissions which resultfrom their use in vehicles. All gasolines sold in California, beginningJun. 1, 1996, have had to meet CARB's Phase 2 requirements as describedbelow, and beginning Jan. 1, 2003, Phase 3 regulations must be met. Thespecifications address the following eight gasoline properties:

-   -   Reid vapor pressure (RVP)    -   Sulfur    -   Oxygen    -   Aromatic hydrocarbons    -   Benzene    -   Olefins    -   Temperature at which 90 percent of the fuel has evaporated (T90)    -   Temperature at which 50 percent of the fuel has evaporated (T50)

The Phase 2 and Phase 3 gasoline regulations include gasolinespecifications that must be met at the time the gasoline is suppliedfrom the production facility. Producers have the option of meetingeither “flat” limits or, if available, “averaging” limits, or,alternatively a Predictive Model equivalent performance standard usingeither the “flat” or “averaging” approach.

The flat limits must not be exceeded in any gallon of gasoline leavingthe production facility when using gallon compliance. For example, thearomatic content of gasoline, subject to the default flat limit, couldnot exceed 25.0 volume percent (see Tables 1 and 2).

The averaging limits for each fuel property established in theregulations are numerically more stringent than the comparable flatlimits for that property. Under the averaging option, the producer mayassign differing “designated alternative limits” (DALs) to differentbatches of gasoline being supplied from the production facility. Eachbatch of gasoline must meet the DAL assigned for the batch. In addition,a producer supplying a batch of gasoline with a DAL less stringent thanthe averaging limit must, within 90 days before or after, supply fromthe same facility sufficient quantities of gasoline subject to morestringent DALs to fully offset the exceedances of the averaging limit.Therefore, an individual batch may not meet the California Phase 2 orPhase 3 Predictive Model when using averaging, but in aggregate, overtime, they must.

The Phase 2 and Phase 3 gasoline regulations also contain “cap” limits.The cap limits are absolute limits that cannot be exceeded in any gallonof gasoline sold or supplied throughout the gasoline distributionsystem. These cap limits are of particular importance when theCalifornia Predictive Model or averaging is used.

A mathematical model, the California Predictive Model, has also beendeveloped by CARB to allow refiners more flexibility. Use of thepredictive model is designed to allow producers to comply with the Phase2 or Phase 3 gasoline requirements by producing gasoline tospecifications different from either the averaging or flat limitspecifications set forth in the regulations. However, producers mustdemonstrate that the alternative Phase 2 or Phase 3 gasolinespecifications will result in equivalent or lower emissions compared toPhase 2 or Phase 3 gasoline meeting either the flat or averaging limitsas indicated by the Predictive Model. Further, the cap limits must bemet for all gasoline formulations, even alternative formulations allowedunder the California Predictive Model. When the Predictive Model isused, the eight parameters of Tables 1 and 2 are limited to the caplimits.

In general, the California Predictive Model is a set of mathematicalequations that allows one to compare the expected exhaust emissionsperformance of a gasoline with a particular set of fuel properties tothe expected exhaust emissions performance of an appropriate gasolinefuel. One or more selected fuel properties can be changed when makingthis comparison.

Generally, in a predictive model, separate mathematical equations applyto different indicators. For example, a mathematical equation could bedeveloped for an air pollutant such as hydrocarbons; or, a mathematicalequation could be developed for a different air pollutant such as theoxides of nitrogen.

Generally, a predictive model for vehicle emissions is typicallycharacterized by:

-   -   the number of mathematical equations developed,    -   the number and type of motor vehicle emissions tests used in the        development of the mathematical equations, and    -   the mathematical or statistical approach used to analyze the        results of the emissions tests.

The California Predictive Model is comprised of eighteen (18)mathematical equations. One set of six equations predicts emissions fromvehicles in Technology Class 3 (model years 1981-1985), another set ofsix is for Technology Class 4 (model years 1986-1995), and another setfor Technology Class 5 (model years 1996-2005). For each technologyclass, one equation estimates the relative amount of exhaust emissionsof hydrocarbons, the second estimates the relative amount of exhaustemissions of oxides of nitrogen, and four are used to estimate therelative amounts of exhaust emissions of the four toxic aircontaminants: benzene, 1,3-butadiene, acetaldehyde, and formaldehyde.These toxic air contaminants are combined based on their relativepotential to cause cancer, which is referred to as potency-weighting.

In creating the California Predictive Model, CARB compiled and analyzedthe results of over 7,300 vehicle exhaust emissions tests. A standardstatistical approach to develop the mathematical equations to estimatechanges in exhaust emissions was used based upon the data collected. Itis appreciated that the California Predictive Model might change withregard to certain of the components considered and their limits. Infact, at present, as discussed above, there exists a California Phase 2Predictive Model and a California Phase 3 Predictive Model. However, itis believed that the present invention and its discovery that a blendingprocess can be used to effectively create the gasolines of the presentinvention, can be used to blend a gasoline in compliance with thespecifications of any California Predictive Model.

In summary, specific requirements were created by the California AirResources Board to restrict the formulation of gasoline to ensure theproduction of gasoline which produces low emissions when used inautomobiles. The present invention provides one with a method ofblending a low emission, oxygenate free gasoline economically and in acommercially plausible manner. The gasoline obtained is in compliancewith the California Predictive Model, at present, either the Phase 2Predictive Model or the Phase 3 Predictive Model, and it containssubstantially no oxygenates. The gasoline is also in compliance withASTM D4814. By substantially free of oxygenates, for the presentinvention, is meant that there is less than 0.1 wt. %, more preferablyless than 0.05 wt. %, and most preferably less than 0.01 wt. % of oxygenattributable to oxygen containing compounds in the blended gasoline. Thegasoline of the present invention is also low in sulfur content, withthe sulfur content being about 20 ppm wt. or less. It is most preferredthat the sulfur content is less than 15 ppm wt., more preferably lessthan 10 ppm wt., even more preferably less than 5 ppm wt., and mostpreferably less than 1 ppm wt. The amount of sulfur can be controlled byspecifically choosing streams which are low in sulfur for blending inthe gasoline. It has been found that the use of low sulfur permits oneto more easily and economically blend a gasoline which is substantiallyfree of oxygenates, yet still complies with the California PredictiveModel for emissions. Thus, the low sulfur content is an important aspectof the present invention.

The gasoline compositions of the present invention also preferably havea T₅₀ of less than 210° F., or preferably less than 200° F., and mostpreferably about 185° F. or less, when Phase 2 gasoline is beingblended, preferably less than 203° F., more preferably less than 200°F., and most preferably less than 190° F. if Phase 3 gasoline is beingblended. The olefin content is also less than 8 vol. %, more preferablyless than 6 vol. %, and most preferably less than 3 vol. %. The amountof benzene is also less than 0.7 vol. % and less than 0.5 vol. % in themost preferred embodiment.

As the gasoline of the present invention is designed for the summermonths, the RVP is generally lower. The RVP is generally about 7.2 orless, and more preferably about 7.0 or less.

The gasoline of the present invention can also be blended to achieve anyoctane rating (R+M)/2 desired. A regular gasoline with an octane ratingof at least 87, a mid-grade gasoline with an octane rating of at least89 or 90, or a premium gasoline with an octane rating of at least 91 or92 can all be prepared in accordance with the present invention.

In a preferred embodiment, the summer gasoline composition of thepresent invention contains less than 0.05 wt % oxygenates, and less than20 ppm wt. sulfur, and more preferably less than 10 ppm wt. sulfur.

The method of the present invention comprises continuously blendinggasoline component streams from refinery process plants. Any of theconventional gasoline component streams which are blended into gasolinescan be used.

A schematic of a suitable system is shown in FIG. 1 of the Drawing. Thegasoline component streams are provided at 1, and flow through componentpump and flow meters 2. Component control valves 3 control how much ofeach stream is let into the blending process 4, to create the blendedgasoline. The blended gasoline is then generally stored in a gasolineproduct tank 5.

To begin the process, a blending model can be used to approximate theblending of the gasoline. Such blending models can be created viaexperience of blending gasolines in compliance with the CaliforniaPredictive Model. They help to predict compliance with the CaliforniaPredictive Model and are important tools in beginning the process. It isgenerally important, however, to include an analysis of the blendedgasoline to maintain compliance of the California Predictive Model. Suchtesting can be periodic or continuous. In general, it is preferred touse an on-line analyzer as shown at 6. Generally, the analysis runinvolves the entire boiling range of the gasoline, including T₅₀ andT₉₀, the RVP of the blended gasoline, the benzene/aromatics content, theolefins content, the oxygenates content and the sulfur content. Thetests run can be as follows:

For distillation, the analyzer utilizes an Applied Automation SimulatedDistillation Motor Gasoline Gas Chromatograph. This analyzer is similarto the instrument described in ASTM D 3710-95: Boiling RangeDistribution of Gasoline by Gas Chromatography. This test method isdesigned to measure the entire boiling range of gasoline, either high orlow Reid Vapor Pressures, and has been validated for gasolinescontaining the oxygenates methyl tertiary butyl ether (MTBE) andtertiary amul methyl either (TAME). Alternatively, the ASTM D86distillation method can be used, although not preferred for an on-lineanalyzer. Either test can be run.

Measuring RVP utilizes an ABB Model 4100 Reid Vapor Pressure Analyzer.This analyzer is described in ASTM D 5482-96. This is a substitute forthe “CARB RVP” calculation based on the Dry-Vapor Pressure result fromD5191, which is itself a substitute for ASTM method 393-89. Either canbe used.

The method for measuring benzene and aromatic content can utilize theApplied Automation Standard Test Method for Determination of Benzene,Toluene, C8 and Heavier Aromatics, and Total Aromatics in Finished MotorGasoline Gas Chromatograph. The analyzer is similar to the instrumentdescribed in ASTM D 5580-95: Standard Tests Method for Determination ofBenzene, Toluene, Ethylbenzene, p/m-Xylene, C9 and Heavier Aromatics,and Total Aromatics in Finished Gasoline by Gas Chromatography. This isa substitute for ASTM D5580 and ASTM D1319 (for aromatics) and ASTMD3606 (for benzene) methods which methods can also be used.

Olefin content can be measured using any suitable method. ASTM D1319 ispresently preferred. Other methods can also be used.

For oxygenates, the method utilizes an Applied Automation Oxygenate GasChromatograph. The method is designed to quantify the amount of methyltertiary butyl ether (MTBE), ethyl tertiary butyl ether (ETBE), andtertiary amyl methyl ether (TAME) in a hydrocarbon matrix. This is asubstitute for ASTM D4815 distillation method, which can also be used.

For measurement of sulfur content, the analyzer can utilize an ABB Model3100 Sulfur in Gasoline Gas Chromatograph. The method is designed toquantify the amount of sulfur in a hydrocarbon steam as a substitute forthe ASTM D2622 or D5454-93 method, which can also be used.

The information from the analysis is then fed to a computer 7 which cancontrol the component flows to produce a gasoline blend which complieswith the California Predictive Model for the summer season. Theinformation provided to the computer can comprise information fromon-line analysis, as well as information from an analysis conducted in alaboratory 8. If desired, tank information and blend specifications forthe gasoline in the product tank can also be provided to the computer.Samples can be drawn from the gasoline product tank, for example, at 9,for laboratory testing.

It has been discovered that a gasoline can be economically and feasiblyblended, particularly on a continuous basis, using the streams from arefinery, despite variations in those streams, to achieve a blendedgasoline meeting the specifications of a California Predictive Model. Byeliminating oxygenates, such as MTBE, the number of gasoline blendspossible to meet the predictive model becomes much smaller. Moreover,the gasoline compositions of the present invention have an RVP of 7.2,and preferably 7.0 or less, making the blending of such compositionsvery difficult. As the octane rating (R+M)2 increases, the number ofsuitable formulations generally decreases even more. Yet, it has beenfound that the blending system of the present invention can stilleconomically and feasiblely provide such a blended gasoline suitable forthe summer season compliant with the California Predictive Model, whilebeing substantially oxygenate free. An example of the reduction in thegasoline blends suitable once MTBE is eliminated, can be betterappreciated upon a review of FIGS. 2 and 3.

In FIG. 2 of the Drawing, the central portion enclosed by the variouslines indicates the various gasoline blends that would meet therequirements for conventional gasoline. In FIG. 3, this portion (whichindicates the amount of gasoline formulations suitable) is reduced dueto the requirements of the California Predictive Model, but the space isstill workable. When one requires substantially no oxygenates, however,the compositions must fall close to the line A shown in FIG. 3, thus,substantially limiting the number of gasoline blends possible.

It has been discovered by the inventors than one can in factsuccessfully and economically blend a summer grade gasoline compliantwith a California Predictive Model which is substantially free ofoxygenates. It is preferred, in the blending, that testing occurs toassure that the blending of the gasoline results in a blended gasolinewhich is compliant with a California Predictive Model. It has beendiscovered that such analysis, particularly when on-line, can quicklyresult in the necessary adjustments to provide a compliant gasoline.

The process of the present invention, therefore, can be used to preparean economic gasoline, which blended gasoline meets a CaliforniaPredictive Model, presently either Phase 2 or Phase 3, and hence thespecifications of CARB. The blended gasoline is economic in that itinvolves the blending of component streams received directly from arefinery, yet the gasoline also contains substantially no oxygenates.

The present invention will be further illustrated by the followingExample, which is provided purely for illustration and is not meant tobe unduly limiting. Where percentages are mentioned in the followingExample, and throughout the specification, the parts and percentages areby weight unless otherwise specified.

EXAMPLES

Several blended gasolines were made using the blending system depictedin FIG. 1, with an on-line analyzer. The blended gasolines are deemed tobe in compliance with the California Phase 2 and Phase 3 PredictiveModels.

The various component streams used were conventional gasoline componentstreams including:

-   -   (i) light petroleum-butane/pentane;    -   (ii) pentane/hexane;    -   (iii) hydrobate (reformer feed);    -   (iv) reformate;    -   (v) FCC gasoline;    -   (vi) alkylate;    -   (vii) toluene.        All of the foregoing component streams were provided from the        same refinery. However, any one of the streams used, and        particularly toluene, can be provided from an outside source,        but it is preferred for the present invention that the component        streams originate as streams in the refinery on site.

Provided below are the qualities of the gasolines successfully blendedin accordance with the present invention. This example demonstrates thatsuch summer grade gasoline can be successfully blended using gasolinecomponent streams from a refinery so as to comply with the CaliforniaPredictive Model, yet contain substantially no oxygenates.

Examples Blend Qualities No. 1 No. 2 No. 3 No. 4 RVP psi 6.82 6.71 6.666.69 Oxygen, wt % 0.03 0.06 0.02 0.04 Gravity API 62.8 63.7 63.0 61.6Aromatics LV % 21.9 21.2 22.7 24.3 Olefins LV % 3.6 4.1 7.3 3.2 BenzeneLV % 0.7 0.68 0.53 0.72 Sulfur, ppm 16 18 14 17 D-86 50 F. 206 200 203202 D-86 90 F. 278 281 290 284

While the invention has been described with preferred embodiments, it isto be understood that variations and modifications may be resorted to aswill be apparent to those skilled in the art. Such variations andmodifications are to be considered within the purview and the scope ofthe claims appended hereto.

1. A method of blending unleaded gasolines which are substantially freeof oxygenates, which have a Reid vapor pressure of 7.00 or less, whichmethod comprises (a) blending some or all gasoline component streamsfrom an oil refinery and keeping the blend substantially free ofoxygenates, and of a sulfur content of less than 10 ppmw, and (b)controlling the blending of the streams such that the blended unleadedgasoline is in compliance with the California Predictive Model.
 2. Themethod of claim 1, wherein the blending of the streams from an oilrefinery is on a continuous basis.
 3. The method of claim 1, whereintesting of the blended unleaded gasoline is conducted for compliancewith the California Phase 3 Predictive Model, and necessary adjustmentsin the blends based on the results of the testing are made to maintaincompliance with the California Phase 3 Predictive Model.
 4. The methodof claim 3, wherein the testing is conducted on a continuous basis. 5.The method of claim 3, wherein the testing is conducted on a periodicbasis.
 6. The method of claim 2, wherein testing of the blended unleadedgasoline is conducted for compliance with the California Phase 3Predictive Model, and necessary adjustments in the blends based on theresults of the testing are made to maintain compliance with theCalifornia Phase 3 Predictive Model.
 7. The method of claim 1, whereinthe streams are blended such that the blended gasoline has an octane ofat least 87 (R+M)/2.
 8. The method of claim 1, wherein the streams areblended such that the blended gasoline has an octane of at least 89(R+M)/2.
 9. The method of claim 1, wherein the streams are blended suchthat the blended gasoline has an octane of at least 92 (R+M)/2.
 10. Themethod of claim 1, wherein the streams are blended such that the blendedgasoline has an octane of at least 90 (R°M)/2.
 11. The method of claim1, wherein the streams are blended such that the blended gasoline is incompliance with the flat specification compliance option of CARB. 12.The method of claim 1, wherein the streams are blended such that theblended gasoline is in compliance with the averaging specificationcompliance option of CARB.
 13. The method of claim 1, wherein thestreams blended are blended such that the resulting blended gasolinecontains less than 0.1 wt. % oxygenates.
 14. The method of claim 1,wherein the streams are blended such that the blended gasoline containsless than 0.05 wt. % oxygenates.
 15. The method of claim 1, wherein theblended gasoline contains less than 5 ppm sulfur.
 16. The method ofclaim 1, wherein the blended gasoline contains less than 1 ppm sulfur.17. The method of claim 1, wherein the streams are blended such that theblended gasoline contains less than 8 vol. % olefins.
 18. The method ofclaim 17, wherein the blended gasoline contains less than 6 vol. %olefins.
 19. The method of claim 17, wherein the blended gasolinecontains about 3 vol. % olefins or less.
 20. The method of claim 1,wherein the streams are blended such that the blended gasoline exhibitsa T₅₀ of less than 203° F.
 21. The method of claim 20, wherein theblended gasoline exhibits a T₅₀ of less than about 200° F.
 22. Themethod of claim 1, wherein the streams are blended such that the blendedgasoline contains about 0.70 vol. % benzene or less.
 23. The method ofclaim 1, wherein the streams are blended such that the blended gasolinecontains less than 0.5 vol. % benzene.
 24. A blended unleaded gasolinecomposition prepared by the method of claim
 1. 25. The gasolinecomposition of claim 24, wherein the blended gasoline composition has anoctane of at least 87 (R+M)/2.
 26. The gasoline composition of claim 24,wherein the composition has an octane from of at least 89 (R+M)/2. 27.The gasoline composition of claim 24, wherein the gasoline has an octaneof at least 92(R+M)/2.
 28. The gasoline composition of claim 24, whereinthe gasoline has an octane of at least 90 (R+M)/2.
 29. The gasolinecomposition of claim 24, wherein the composition contains less than 0.5wt. % oxygenates.
 30. The gasoline composition of claim 24, wherein thecomposition contains less than 0.1 wt. % oxygenates.
 31. The gasolinecomposition of claim 24, wherein the composition contains less than 0.05wt. % oxygenates.
 32. The gasoline composition of claim 24, wherein thecomposition contains less than 5 ppm wt. sulfur.
 33. The gasolinecomposition of claim 24, wherein the composition contains less than 1ppm wt. sulfur.
 34. The gasoline composition of claim 24, wherein thecomposition contains less than 8 vol. % olefins.
 35. The gasolinecomposition of claim 24, wherein the composition contains less than 6vol. % olefins.
 36. The gasoline composition of claim 24, wherein thecomposition contains less than 3 vol. % olefins.
 37. The gasolinecomposition of claim 24, wherein the composition exhibits a T₅₀ of lessthan 203° F.
 38. The gasoline composition of claim 24, wherein thecomposition exhibits a T₅₀ of less than 200° F.
 39. The gasolinecomposition of claim 24, wherein the composition contains about 0.70vol. % benzene or less.
 40. The gasoline composition of claim 24,wherein the composition contains less than 0.5 vol. % benzene.
 41. Anunleaded gasoline composition which is substantially free of oxygenates,is in compliance with the California Code of Regulations, and has asulfur content of less than 10 ppmw.
 42. An unleaded gasolinecomposition which is substantially free of oxygenates, is in compliancewith California Phase 2 reformulated gasoline regulations, and has asulfur content of less than 10 ppmw.